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Contents..........................................................................................................................................1 Data Warehousing questions...........................................................................................................1 SQL questions.................................................................................................................................1 Unix questions................................................................................................................................3 Informatica Questions.....................................................................................................................5 Multiple Choice & True/False Questions...................................................................................5
Data Warehousing questions
1. What is Data Warehousing? Why do we need it?
2. What is ad hoc analysis?
3. Describe OLAP and OLTP systems
OLAP vs. OTLP: list five main differences.
4. What is a fact table in a dimensional model? What is a dimension table?
5. Characterize STAR and SNOWFLAKE schemas.
6. What is a Slow Changing Dimension?
List all known types; describe implementation techniques.
7. What is a lookup table?
8. Why do we need Dimension Normalization?
9. List and describe storage models supporting multidimensional analysis (list pros and cons for each).
10. What is ETL?
11. What is a Data Mart?
12. Describe Slice and Dice techniques.
13. What is the main difference between Kimball’s and Inmon’s approaches?
14. What is a data mining?
List and describe data mining tasks.
SQL questions
1. What does the abbreviation SQL stand for?
2. How would you list all the records in a table?
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3. What is SQL92?
For the next part, let's define the following entities and relationships: entity CUSTOMER
attributes: CUSTOMER_ID, CUSTOMER_NAME entity ACCOUNT
attributes: ACCOUNT_NO, CUSTOMER_ID, BALANCE entity EMPLOYEE
attributes: EMPLOYEE _ID, EMPLOYEE_NAME, REPORTS_TO entity PROJECT
attributes: PROJ_ID, PROJ_NAME, PROJ_LOCATION_ID, PROJ_CITY
The following business rules must apply:
The field REPORTS_TO is null for exactly one employee, otherwise it is one of the numbers found in column EMPLOYEE_ID
Each employee can work on several projects Each project can have multiple locations
PROJ_CITY can be derived from PROJ_LOCATION_ID
4. Draw/design tables for above business cases in accordance with 3-rd Normal Form (you can defer the data types)
5. What is ER model?
6. What is normalization? List all known normal forms.
7. Describe 3-rd normal form
8. How would you update a single customer's name in a customer table? Make up a simple scenario and write the query.
9. What is a primary key?
List all PKs in the tables you have designed.
10. What is a foreign key?
List all FKs in the tables you have designed.
11. What is a relation?
12.What is a relationship? What is referential integrity?
13. What is a join?
Name all types of joins.
14. What is a rollback?
15. What is a transaction log?
16.What operation (SELECT, INSERT, UPDATE, DELETE) has the highest impact on transaction log?
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17. What is an index? How is it created? What is its purpose?
How much space does it require? When and how is it used?
List and explain some of the physical index types.
For the next part, write down SQL queries. Assume that all necessary referential and domain integrity controls + take place.
18. Find out how many customers we have.
19. Set up an initial account for a new customer with balance $100.
20. List all duplicate customer names (occurring more than once), including frequency of occurrence.
21.List all customers (by names) that have more than $1000 in total combined on all their accounts.
22. Find out how many customers have more than 2 accounts.
23. Report a simple statistics: number of customers having exactly 1 accounts, 2 accounts, etc. (in one query).
24. Delete a customer and all his/her accounts.
25. List all subordinates to the employee with ID=123 on level 1 (i.e. employees that directly report to 123).
26. List all subordinates to the employee with ID=123 on level 2 (i.e. those that report to someone reporting to 123).
For the next part, the queries are more complex and tricky. Feel free to attach some comments if necessary.
27. List ALL subordinates to the employee with ID=123 (i.e. anyone under 123).
28. Find out the maximum subordinate level (i.e. the depth of the employee tree).
Unix questions
1. How do you list contents of a directory?
2. How do you display contents of a file? How to display first 10 lines?
How to display last 200 characters of a file?
3. How do you check for running processes?
4. How do you kill a process?
5. How do you check who's logged in?
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6. How do you get help on a UNIX terminal? 7. Give examples of remote access to a machine.
8. What is the shell?
Describe purpose of the shell (name 5 shells) 9. What is the kernel?
10. How to compare two text files if they are identical? 11. What is mounting means? Describe the command. 12. What is permission of a file?
How to change the permission and ownership of a file?
13. What ‘.’ (dot) before file name means (.filename)?
What will happen if you type “.” (dot) before file name in command prompt (. 16. What is a file system? How do you get its usage? 17. How do you check the sizes of all users' home directories (one command)? 18. How do you check for processes started by user \"pat\"? 19. How do you start a job on background? How to send job to background? How to bring current job to the foreground? How to suspend the foreground job? 20. What utility would you use to replace a string \"2001\" for \"2002\" in a text file? 21. What is a signal? Give some examples. 22. How to display statistics about memory usage? 23. How do you list contents of a directory and all of its subdirectories, providing full details, but only regular files that haven't been accessed in the last 2 days? 24. How do you delete all files older than I year from a directory? 25. What is a named pipe? How to create and use one? 26. What is an I-node? How many I-nodes are there per file if the file is 1 KB is size, or 1 MB is size? 4 27. What utility would you use to swap columns 1 and 2 in a text file? 28. What utility would you use to cut off the first column in a text file? Informatica Questions Multiple Choice & True/False Questions 1. Which one of the following is not an active transformation: (a) Aggregator (b) Router (c) Filter (d) Expression 2. If you click on “Group by” for all ports in the Aggregator transformation, how many rows would be output? (a) One row (b) All rows (c) No rows 3. You can edit data dynamically while in the Debugger. (a) True (b) False 4. Which one of the following hierarchies is correct: (a) Worklet, Task, Workflow (b) Task, Worklet, Workflow (c) Workflow, Task, Worklet 5. Select the correct order of port processing in an expression transformation: (a) input, output, variable (b) input, variable, output (c) variable, input, output 6. If in_lookup_key = 10, what result will the following expression produce? IIF(ISNULL(in_lookup_key), ‘Key not found’, IIF(in_lookup_key >= 1 and in_lookup_key <=5, ‘Low score’, IIF(DECODE(in_lookup_key, 10, 1, 0), ‘Maximum Score’), ‘High Score’))) (a) ‘Maximum Score’ (b) ‘High Score’ (c) ‘Key not found’ (d) ‘Low Score’ 5 7. The ports listed in a lookup transformation must match the ports in the lookup table exactly, or the lookup transformation will fail. (a) True (b) False 8. The error message “Failed to expand session parameter variables” means: (a) Variables were not defined within the mapping (b) Parameters were not defined within the mapping (c) Parameters were not defined within the parameter file (d) The parameter file was not defined within the session, batch or workflow 9. Which one of these commands is not valid in the update strategy transformation: (a) DD_INSERT (b) DD_UPDATE (c) DD_REJECT (d) DD_DELETE (e) all of the above are valid 10. Which one of the following error tracing levels produces the largest session logs: (a) Verbose Init (b) Verbose Data (c) Terse 11. Sessions can be run from a UNIX shell script: (a) True (b) False Short Answer Questions 12. What is the difference between a parameter and a variable? 13. Describe the difference between active and passive transformations. 14. Describe how you would determine all of the mappings that use a particular target in a folder. 6 7 因篇幅问题不能全部显示，请点此查看更多更全内容